This invention relates to a method of molding a molding resin on a substrate having openings, a switch substrate equipped with a molding resin, a method of forming a switch pattern on a switch substrate, and a switch substrate.
There is available a switch substrate for a rotary encoder which produces a desired coded output by causing a slider to come into sliding contact with contacts while being rotated. FIG. 20 is an enlarged plan view illustrating an example of such a switch substrate for a rotary encoder according to the prior art. The switch substrate shown in FIG. 20 includes a hard insulating substrate 80 on which are provided a first switch pattern group 81, a second switch pattern group 87 and a common switch pattern 93. Terminal connection lands 85, 89 and 95 are led out from the switch pattern groups 81, 87 and common switch pattern 93, respectively. The first switch pattern group 81 is constructed by connecting four code-output switch patterns 84 by a connecting pattern 81a, the second switch pattern group 87 is constructed by connecting four code-output switch patterns 90 by a connecting pattern 87a, and the common switch pattern 93 is formed in the shape of a circular arc.
By causing a slider to make sliding contact with the switch patterns while being rotated along a path indicated by two concentric dot-and-dash lines, a desired coded output is obtained depending upon the position at which the slider makes contact.
If patterns of the printed type are used as the switch pattern groups 81, 87 and common switch pattern 93, i.e., if the patterns are formed by coating a silver pattern with a carbon pattern, for example, paste printing is employed as the forming technique. As a consequence, such portions as sides 82 of the switch patterns 84 and sides 88 of the switch patterns 90 cannot be formed to have accurate and precise dimensions, a variance in position occurs and, as a result, an accurate coded output that conforms to the position of the slider is not obtained.
An example of a method proposed to solve this problem involves forming the switch substrate by punching a metal plate, the shape of which corresponds to the switch pattern groups 81, 87 and common switch pattern 93, by press cutting, and attaching the metal plate to an insulating substrate made of molding resin. A problem which arises, however, is that the manufacturing cost involved with this method is higher than that of the method of printing the switch pattern groups 81 and 87 on the insulating substrate.
Accordingly, an object of the present invention is to provide a method of forming switch patterns on a switch substrate easily, precisely and at low cost.
Another object of the present invention is to provide a method of molding a molding resin on a substrate having openings, wherein the surface of the substrate can be made flat even though the substrate has openings.
According to the present invention, there is provided a method of molding a molding resin on a substrate having openings, comprising preparing a substrate having openings, a first mold and a second mold and clamping the substrate having the openings between the first and second molds in such a manner that one side of the substrate is brought into surface contact with a surface of the first mold while, at the same time, a cavity provided in the second mold is made to oppose the other side of the substrate. A molten molding resin is charged into the cavity provided in the second mold to thereby fill the cavity and the openings of the substrate with the molding resin. The substrate, which has the molding resin attached thereto, is then extracted by separating the first and second molds after the molding resin hardens, thereby molding the molding resin on the substrate having the openings.
The substrate having the openings preferably is a substrate made of synthetic resin and having openings.
In a preferred embodiment, the substrate having the openings is a switch substrate having switch patterns formed on one side thereof, the switch patterns and the openings being situated on a path along which a slider makes sliding contact with the switch patterns.
The second mold preferably is provided with pressing portions for pressing peripheries of the openings of the substrate against the first mold.
In a preferred embodiment, positions at which the pressing portions press the substrate against the first mold are situated at the periphery of the openings but not on the path along which the slider makes sliding contact with the switch patterns.
In a preferred embodiment, the switch substrate is manufactured by the steps of forming patterns on a surface of a substrate in advance, and then providing openings by removing pattern-removal portions of the patterns, thereby forming switch patterns with which the slider makes sliding contact.
Further, according to the present invention, there is provided a switch substrate equipped with molding resin, the switch substrate having switch patterns formed on one side thereof. Openings and the switch patterns are situated on a path along which a slider makes sliding contact with the switch patterns. A molding resin is attached to the substrate in a state in which it is in surface contact with a side of the switch substrate on which no switch patterns are provided. The height of the surface of the molding resin exposed at the openings provided in the switch substrate is made to coincide with the height of the side of the switch substrate on which the switch patterns are provided, thereby constructing a switch substrate equipped with molding resin.
Further, according to the present invention, there is provided a method of molding a molding resin on a switch substrate, comprising manufacturing a switch substrate by forming patterns on a surface of a film-like substrate in advance, then providing openings by removing pattern-removal portions of the patterns to thereby form switch patterns with which a slider makes sliding contact. The switch substrate, a first mold and a second mold are prepared and, the switch substrate is clamped between the first and second molds in such a manner that one side of the switch substrate is brought into surface contact with a surface of the first mold while, at the same time, a cavity provided in the second mold is made to oppose the other side of the switch substrate. A molten molding resin is charged into the cavity provided in the second mold to thereby fill the cavity and the openings of the substrate with the molding resin. The switch substrate, which has the molding resin attached thereto, is then extracted by separating the first and second molds after the molding resin hardens.
Further, the present invention provides a method of forming switch patterns, with which a slider is to make sliding contact, on a switch substrate. The method includes forming patterns on a surface of a substrate in advance, and forming switch patterns by removing pattern-removal portions of the patterns.
The removal step may be removal of the patterns only, or removal, together with the patterns, of the substrate on which the patterns have been formed.
Further, the present invention provides a method of forming switch patterns, with which a slider is to make sliding contact, on a switch substrate. The method includes forming patterns on a surface of a substrate in advance, and forming insulating patterns at portions between these patterns that are to become switch patterns. The switch patterns are formed by removing pattern-removal portions at boundaries between the patterns and insulating patterns.
Further, the present invention provides a switch substrate, in which switch patterns with which a slider is to make sliding contact, are formed on a substrate. Insulating patterns are then formed at portions between the switch patterns.
Many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof. Therefore, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.